From: hacklu <hacklu.uboot@gmail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] how to understand "uboot is 32bit program even it isin the 64bit mips"
Date: Wed, 22 Jun 2011 15:02:33 +0800 [thread overview]
Message-ID: <201106221502272672042@gmail.com> (raw)
In-Reply-To: 201106221006548156815@gmail.com
thanks for you answer. I have got too much.
On 2011-06-22 13:25:34, Aaron Williams wrote:
>We have dealt with this in our release of U-Boot since we only support
>64-bit Linux. We use the n32 ABI with U-Boot and set it up to use a TLB
>entry to map U-Boot into a 32-bit addressable area.
in the U-boot _shell_. I use md command. I found
md 0x100000 and mx0x800100000 are the same.
is that says:the virtual address 0x0 - 0xfffffff(256M, can I called this _kusg_ segment ?)
are mapped to the _physical_ memory address 0x0 - 0xfffffff(256M) with the _TLB_.
and the virtual address 0x80000000 - 0x8fffffff(like that, _kseg0_ ?) is mapped to
the _physical_ memory address 0x0 - 0xfffffff(256M) according to the mips
arch feature.
do I understand correctly?
>We have some special memcpy type routines that can handle the 64-bit
>addressing.
>All of our I/O registers require 64-bit addressing so we use assembly
>wrappers to do the actual read/writes to those addresses.
>-Aaron Williams
>On 06/21/2011 07:07 PM, hacklu wrote:
>> I have a 64bit cnMips borad.In the mail list archives,it says "uboot is 32bit,even in the 64bit cpu."
>> but how to understand that?
>> I have a guess,is the 64bit cpu support a 32bit-mode,then when does it switch to 64bit-mode to load 64-bit linux?
>>
>> btw,I have an other question,according to <see mips run linux>,linux run in the _xkseg_ segment. so the first two bit >>virtual address in kernel space must be 11,
>> like 11xx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx (64bit).
>> but when I printf a variable' address in a foo driver,is say 0xa80000041c2ea180. not start of _11_.
>> the memory mapping mode has feazed me for _long_ _long_time.
I hope you can answer this question for me. I really really want to know this.
thans for your attention.
>> Dear Wolfgang(or someone else who can anwser me),thanks
>>
>>--------------
>> hacklu
>>2011-06-22
>>
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hacklu
2011-06-22
prev parent reply other threads:[~2011-06-22 7:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-22 2:07 [U-Boot] how to understand "uboot is 32bit program even it is in the 64bit mips" hacklu
2011-06-22 5:10 ` Aaron Williams
2011-06-22 7:02 ` hacklu [this message]
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